Disease relapse is the leading cause of mortality for children diagnosed with disseminated neuroblastoma despite the use of highly intensive front-line therapy. Studies conducted in our laboratory have focused on developing strategies to target neuroblastoma with adoptively transferred T lymphocytes genetically modified to express a chimeric immunoreceptor, designated CE7R, for re-directed recognition of a neuroblastoma-specific epitope on the L1-CAM adhesion molecule. The engineering of CE7R was accomplished by assembling a cDNA construct encoding a single-chain antibody extracellular domain derived from the murine CE7 hybridoma fused to the cytoplasmic tail of the T cell receptor CD3 complex zeta chain (scFvFc:zeta). In vitro culture systems have been developed for genetically modifying human T cells with naked plasmid DNA by electroporation and expanding modified clones to numbers in excess of 10e10. Ex vivo expanded CE7R scFvFc:zeta-expressing cytotoxic T lymphocyte (CTL) clones specifically recognize human neuroblastoma tumor cells and are activated for tumor cell cytolysis and cytokine secretion. These pre-clinical studies have provided the rationale to explore the therapeutic utility of cellular immunotherapy with autologous CTL clones engineered to express the CE7R chimeric immunoreceptor and the selection/suicide fusion protein HyTK in children with recurrent/refractory disseminated neuroblastoma. The in vivo persistence, anti-tumor activity, and immunogenicity of infused clones will be assessed following adoptive transfer in order to delineate how the in vivo biology of ex vivo expanded CE7R+ CTL might be further optimized. The specific aims of this project are: 1.) To evaluate the safety and toxicity of adoptively transferred CE7R+/HyTK+ CD8+ CTL clones in children with recurrent/refractory neuroblastoma. 2.) To quantitate the anti-tumor activity of infused clones in patients with measurable disease. 3.) To study the persistence of transferred clones in research participants by Q-PCR and the impact of administering exogenous IL-2 on the duration and magnitude of in vivo persistence. 4.) To assess in this patient population the development of antibody and cellular immune responses against the scFvFc:zeta and HyTK chimeric proteins.